Method and apparatus for manufacture of metal films



Aug. 3, 1954 o. F. DAVIS ET AL 2,685,121

METHOD AND APPARATUS FOR MANUFACTURE OF METAL FILMS Filed May 7, 1949 H. l l ll l 1 H WM M/VE N TORS OLIVER RDAV HANS G. BELITZ, 9

8T TORNEYS Patented Aug. 3, 1954 METHOD AND APPARA TUBE OF ME Oliver F. Davis, Troy, and Hans G. Belitz, Dayton,

Ohio, asslgnors TUS FOR MANUFAC- TAL FILMS to The Commonwealth Engineering Company of Ohio, Dayton, Ohio, a corporation of Ohio Application May 7.

9 Claims. 1

This invention relates to metal foil. More particularly, it relates to a continuous method of producing metal foil or film. Still more particularly it relates to film formation by continuous deposition of metal from the vapor state.

In the past metal foils have been produced by preparing billets of malleable metals or malleable alloys and passing the billets between rollers, which reduced the thickness of the billet by stages.

In the final stages the metal is passed between very accurately machined rolls, and simultaneously therewith the thin metal sheet issuing from between the rolls is drawn by careful application of tensioning stress. The thin drawn metal sheet is then Wound on reels for storage and shipping.

This process is costly and requires large and expensive equipment. In the final stages the maintenance of tension is a delicately balanced operation, which requires constant attention to avoid overstressing the metal and breaking the foil.

Further, the maintenance of accurately machined close clearance rolls, such as are required for the final stages of foil preparation, is a constant expense.

It is an object of the present invention to overcome the disadvantages and the necessity for costly equipment enumerated above.

A further object of the to produce foils or films by deposition of metal.

A still further object of the invention is to produce foils or films without the necessity for expensive roller equipment.

Another object of the produce thin foils or films of any metal which can be deposited from the vapor state.

A further object of the invention is to provide foils of durable structure and excellent fatigue resistance.

Another object of the invention is to provide a process in which a thin film of metal is continuously deposited and the deposited film continuously removed from a revolving base.

A still further object of the invention is to provide apparatus wherein the gaseous medium bearing metal is directed into contact with a rotating heated surface.

In brief, the process consists of impinging a stream of vapor bearing depositable metal upon a continuously rotating cylindrical base or roll. This rotating base is provided with a smooth prepared surface, to which the deposited metal has little adherence.

The non-adhering coating, generally having present invention is present invention is to 1949, Serial No. 91,924

2 a thickness of .005 to about .025 inches, is then stripped from the cylindrical base and the foil removed from the plating chamber for cooling and winding on reels.

This process is given over to the production of two similar types of foil.

which is stripped and remains on the foil. The other type of foil is produced by depositbut their presence usually necessitates a removal step.

Conditioning of the base against adherence of deposited metal may be accomplished by blowresin which does not soften appreciably at a temperature, for example, of 400 F., the temperature at which many carbonyls and hydrides decompose to deposit their metal component.

One simple method of preventing adherence is to cause the drum to rotate in a smoky acetylene flame which deposits carbon soot.

Metals which may be deposited as thin films are, for example, nickel, chromium, copper, tungsten, tin, zinc, lead, and the like.

One particularly advantageous method of bringing metal as vapors into the plating zone is in the form of readily decomposable gaseous compounds. For example, the metals may be introduced as gaseous metal carbonyls, also nitroxyl compounds, nitrosyl carbonyls, metal hydrides, metal alkyls, metal halides, and the like.

Illustrative compounds of the carbonyl type are nickel, iron, chromium, molybdenum, cobalt, and mixed carbonyls.

Illustrative compounds of other groups are the nitroxyls, such as copper nitroxyl; nitrosyl carbonyls, for example, cobalt nitrosyl carbonyl; hydrides, such as antimony hydride, tin hydride; metal alkyls, such as tetraethyl lead; metal halides, such as chromyl chloride; and carbonyl halogens, for example, osmium carbonyl bromide, rhuthenium carbonyl chloride, and the like.

The plating of foil or film may be carried out under a Wide variety of conditions. When undiluted vapors are fed to the plating zone, it is generally preferable to feed the vapors under a slight positive pressure, i. e. a pressure above atmospheric. When dilute vapors are fed to the plating zone, an even wider range of pressures may be used, running from negative pressures usually expressed in inches of water vacuum to positive pressures usually expressed as pounds per square inch gage.

The manner in which the metal bearing vapors are entrained varies from carbureting metal vapors into an inert gas stream maintained under pressure to spraying liquid into hot gas being sucked through the system by vacuum, which gas vaporizes the liquid droplets-whereby the liquid is a vapor in the plating zone.

Each material from which metals may be plated has a temperature at which thernetal in vapor form is free to deposit as a metal coating. When plating there is an optimum plating range for a large number of, for example, metal carbonyls, running fromabout 350 F. to 450 F. Decomposition takes place outside this range, but when seeking uniform'deposits, it is desirable to operate within the above range and evenwithin the range of 375 F. to 400 F.,,,if it is desired to plate nickel, molybdenum, cobalt, and the like.

The above mentioned 350 F. to 450 F. temperature rangeis also useful for decomposition of many of the hydrides. However, since each type of metal and each type of compound alters the plating range, applicants merely offer the above as a range for specific embodiments of the invention and not as a limitation upon the operating range of coating deposition.

The invention will be more fully understood by reference to the drawing:

Figure 1 is a vertical sectional view of apparatus illustrating one embodiment of the invention; and

Figure 2 is a plan view showing the relationship of thevapor conductor hood to the metal plating roll.

The apparatus consists of a chamber which is provided with a jacket ll. Chamber i0 is also provided with a gas outlet l2 which may, if desired, be connected to exhaust means (not shown) suchv as an exhaust fan or vacuum pump.

Jacket II is provided with inlet means l3 and outlet means 14 for, introduction and removal of cooling medium from the jacket.

Mounted within the chamber i0 is a cylindrical roll or drum 16. of suitable construction material such asglass. Drum I8. is. supported on a shaft ll suitably journaled in the. walls of chamber lfl and driven by-a prime mover such as an electricmotor stationed outside the chamber through a suitable coupling and speed reduction gear.

Drum: I6 is provided internally but adjacent its peripheral area with heating meansZQ, such as electrical. resistance coils, induction coils, and the like, whose electrical circuitis connected to asourceot power througha suitable brush arrangement mounted on shaft: 11.

Metal bearing gases are introduced into chamber Ill-through conduit 2!. .Conduit 2i isprovidedat its inner end with a hood like portion 22 adapted to direct inflowing gases into contact with a large area of thesurface of the roll.

Tangentially positioned in contact with the exterior of the roll i6 is a doctor blade 23 adjustable by screw. 24. This blade serves for stripping coated deposits from the roll.

Metal stripped from the roll by the doctor blade is directed. between rollers25 closing the aperslow travel of the drum through degrees from the point of application.

The drum is maintained at a temperature of approximately 400 F. In order to start a run a thin layer of copper is passed between the rollers 3| and 25 and is molded to conform to the shape of the roll [6.

A stream of, for example, nickel carbonyl vapors flowing atthe. rate of cubic feet per hour, diluted with carbondioxide is brought into contactwith th roll l6 through conduit. 2 l.

The carbon dioxide and gaseous decomposition products are exhausted through outlet means l2.

When deposition has become appreciable winding of the reel and rotation of roll- I5 is initiated.

Due to th adherence of nickel tocopper the nickel film is drawn out through lock rollers 25,

is cooled in an inert atmosphere while traversing chamber 28, and is passed through the lock rollers 35 to the winding reel.

Chamber 28 is maintained under a slightly higher gas pressure than chamber In which action prevents leakage of toxic gases from chamber l0.

While the method and apparatus disclosed-and described herein. illustrate a preferred form of invention, yet it will beunderstood that modifications can be made without departing from thev spirit of the invention, and that modifications that fall within the scope of the appended claims are intended to be included herein.

We claim:

1. Th method of preparing metal foil which comprises, maintaining a cylindrical roll in continuous revolving motion, coating a substantially cleared surface of the roll with an adherencereducing medium, heating said roll to a temperature in the range of 350 F. to 450 F., impinging a gaseous stream of inert gas and metal carbonyl against said heated revolving-roll whereby the carbonyl is decomposed and the metal deposited to produce a thin film on said roll, andcontinuously stripping the thin film of deposited metal from said roll.

2. Th method of preparing-metal foil which comprises, maintaining a cylindrical roll in-continucus revolving motion, coating a substantially cleared surface of the roll with an adherencereducing medium, heating said roll to a temperature in the range of 350 F. to'450 F., impinging a gaseous stream of inert gas and a metal carbonyl against said heated revolving roll whereby the carbonyl isdecomposed and the metal deposited to produce a thin film on said roll, and continuously stripping the thin film ofdeposited metal from said roll, said metal carbonyl being selected from the group-consisting of nickel carbonyl, iron carbonyl, and cobalt carbonyl.

3. The method of preparing metal foilwhich comprises, maintaining a cylindrical roll in continuous revolving motion, coating a-substantially' cleared surface of the roll with'an adherencereducing medium, heating said roll to a temperature in the range of 350 F. to 450 F., impingin a gaseous stream of inert gas and metal hydride against said heated revolving roll whereby the hydride is decomposed and the metal deposited to produce a thin film on said roll, and continuously stripping the thin film of deposited metal from said roll.

4. The method of preparing metal foil which comprises, maintaining a cylindrical roll in con- F. to 450 F., impinging a gaseous stream of inert gas and a metal hydride against said heated revolving roll whereby the hydride is decomposed and the metal deposited to produce a thin film on said roll, and continuously stripping the thin film of deposited metal from said roll, said metal hydride being selected from the group consisting of tin hydride and chromium hydride.

5. The method of preparing metal foil which comprises, maintaining a cylindrical roll in continuous revolving motion, coating a substantially cleared surface of the roll with Carnauba wax, heating said roll to a temperature of approximately 390 F., impinging a gaseous stream of carbon dioxide and nickel carbonyl against said heated revolving roll whereby the carbonyl is dethe nickel is deposited on said roll to a depth of approximately .025 inch, maintaining a pressure in the coating area of approximately 3 inches of water vacuum, and continuously stripping the nickel film from said roll.

6. Apparatus for the preparation of metal foils comprising a chamber, a cylindrical roll mounted within said chamber, means for rotating said roll, means for heating said roll, means for introducing heat-decomposable metal bearing vapors into contact with said roll, outlet means for removing vapors from said chamber, and cutting means in contact with said roll for stripping deposited metal film from said roll.

'7. Apparatus for the preparation of metal foils comprising a chamber, a jacket associated with said chamber, inlet and outlet means for circuin contact therewith for stripping deposited metal from said roll.

8. Apparatus for the preparation of metal foils chamber, a secondary chamber, inlet and outlet means for circulating gaseous medium, gas tight roller locks between the primary and secondary chamber for passage of foil therebetween, and locking rollers for removal of foil from secondary chamber to reeling apparatus.

9. In a method of preparing metal foil com prising the steps of depositing a thin metal coating on a rotating cylinder, the improvement which consists in depositing the metal forming the foil as a heat-decomposable gaseous metal compound, and wherein said cylinder is heated to a temperature References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,344,138 Drummond Mar. 14, 1944 FOREIGN PATENTS Number Country Date 14,845 Great Britain June 21, 1907 17,115 Great Britain July 19, 1910 39,453 Denmark Oct. 27, 1928 454,919 Great Britain Oct. 5, 1936 

